On a display unit of an active matrix-type liquid crystal display device, a plurality of pixel formation portions are formed in a matrix. In each of the pixel formation portions, there are provided: a thin film transistor (hereinafter, referred to as a “TFT”) that operates as a switching element; and a pixel capacitance connected to a data signal line through the TFT. By switching on/off this TFT, a data signal for displaying an image is written as a data voltage into the pixel capacitance in the pixel formation portion. This data voltage is applied to a liquid crystal layer of the pixel formation portion, and changes an orientation direction of liquid crystal molecules to a direction corresponding to a data voltage value. As described above, the liquid crystal display device controls a transmittance of the liquid crystal layer of each pixel formation portion, and displays an image on the display unit.
However, in the liquid crystal display device as described above, if a power supply is turned off when the image is displayed on the display unit, the TFT of each pixel formation portion also turns to an OFF state. The data voltage held in the pixel capacitance in the pixel formation portion at this time is also held thereafter in a state of maintaining a value thereof. That is, even after the power supply is turned off, a stored charge equivalent to the data voltage remains in the pixel capacitance. Therefore, in a case where an off-leak current of the TFT in the pixel formation portion (that is, a current flowing through the TFT when the power supply is in an off state) is small (for example, in a case of a TFT using an oxide semiconductor such as indium gallium zinc oxide for the channel layer), a direct current voltage is applied thereto continuously, whereby there occurs a problem that an afterimage formed by burn-in of liquid crystal is generated when the power supply is thereafter turned on, and that a flicker caused by deviation of an optimum common voltage is generated (hereinafter, this problem is referred to as a “problem such as generation of flicker”).
In particular, the problem such as the generation of the flicker is likely to occur in “pause drive” using the TFT with a small off-leak current. Here, the pause drive is a drive method of alternately providing scanning periods of scanning scanning signal lines and refreshing a display image (also referred to as “refresh periods”) and pause periods of turning all of the scanning signal lines to a non-scanning state and pausing the refreshment (also referred to as “refresh periods”) in order to reduce power consumption of the liquid crystal display device.
As opposed to this, Japanese Patent Application Laid-Open No. 2011-85680 describes a configuration of controlling a potential of each of the scanning signal lines so that an OFF resistance of the TFT can be decreased before turning off the power supply in an off-sequence operation. In accordance with this configuration, the voltage held in the pixel formation portion is cleared quickly, and accordingly, the stored charge is unlikely to remain in the pixel formation portion when the power supply is turned off.